Engineering consultancy Ricardo has completed initial testing of its innovative 2/4-stroke engine prototype.

This innovative 2/4Sight petrol engine, first reported here two years ago, has a direct-injection system with modified intake/exhaust ports, valve timing, boost supply and ignition which enables running in both two- and four-stroke modes, and seamless switching between the two modes.

The engine also incorporates a turbocharger and supercharger; a 2.1-litre V6, it is said to offer performance equivalent to that of a 3.4 V8, as well as fuel savings and much-reduced carbon dioxide emissions. Tested in a simulation of a 1,800kg large family car, it returned fuel economy improved by 27% compared to that car's usual 3.5 V6, and carbon dioxide emissions reduced from 260g/km to 190g/km, yet maintained its performance.

Ricardo has also developed a patented mechanical cam switching system to be used in the 2/4Sight engine. This 'represents a highly cost-effective means of implementation of this highly efficient combustion concept', says the company, and 'opens the way for packaging and integration of the 2/4Sight engine into a production vehicle'.

Ricardo spokesman Neville Jackson added: 'While significant further research and development challenges remain, not least in the vehicle demonstration of this advanced engine concept, the initial prototype development project has demonstrated the potential of 2/4Sight to offer improved gasoline fuel economy and reduced CO2 emissions, while also maintaining or improving vehicle performance. In addition to validating the 2/4Sight concept, the research project is also delivering significant benefits in terms of its many constituent technologies which are likely to see application in the more immediate term.'